Double lift dobbies



May 7, 1968 M. FAVRE DOUBLE LIFT DOBBIES 4 Sheets-Sheet 1 Filed June 1,1966 Q Q QR Q Q m a m i m May 7, 1968 M. FAVRE 3,381,719

DOUBLE LIFT DOBBIES Filed June 1, 1966 4Sheecs-Sheet z UUUUUUUUUUUUU May7,1968 M. FAVRE DOUBLE LIFT noaams 4 Sheets-Sheet 3 Filed June 1, 1966May 7, 1968 M. FAVRE DOUBLE LIFT DOBBIES 4 Sheets-Sheet '4 Filed June 1.1966 w v a J J m e W 6 w a m U w n m M m n m m n u m u u D n n 0m n n ma.3 u .a .w u an ham Q. n n u n a m E n u u k u .8 m: n .5 .5 u n. m: n nH u v n u II/ n u n S 8 B United States Patent 3,381,719 DOUBLE LIFTDOBBIES Marcel Favre, Faverges, France, assignor to Gebr. Staubli & C0.,Zurich, Switzerland Filed June 1, 1966, Ser. No. 554,501 Claimspriority, application France, June 1, 1965,

5 Claims. (cl. 139-68) ABSTRACT OF THE DISCLOSURE A double lift dobby inwhich the baulks are arrested by arrester hooks actuated by two groupsof draw needles. Each group is made of a pair of these needles and eachneedle of the pairs is associated with only one of the two arresterhooks arresting a respective baulk. The draw needles are actuated bydraw rails operating out of phase with one lagging the other slightly bya double pick and the draw needles of a same group by one pick in theworking cycle of the dobby. The working cycle of the dobby is equivalentto two picks corresponding to 360. The draw needles of the variousgroups are actuated without a jerky operation of the arrester hooks. Thebaulks are actuated at respective ends by pusher rails drivenreciprocably out of phase 180 for each double pick. The draw needlesthemselves are associated with reading needles reading a pattern card sothat the desired baulks are arrested in a forward position correspondingto a raised heald position under control of the pattern card.

The present invention relates to a double lift dobby, wherein a baulk isassociated with each jack of a heald shaft. The ends of each baulk haveon the one-hand pivoted attachment hooks and on the other hand aremovable in opposite directions of movement by two pusher rails swingingto-and-fro, which contact the same and are angularly offset 180 perdouble pick of the 360 working cycle of the dobby. The attachment hookswith their baulk ends are capable of being arrested by arrester hooksfor the purpose of raising the heald shaft, and each arrester hook iscontrollable by a pair of draw needles. Four draw needles associatedwith each heald shaft and cooperate with reading needles and beingsubdivided into two groups for forward and reverse run, each comprisingtwo reading needles. These groups read the rows of perforations of apattern card in conjunction with, but offset relative to, one another bya double pick unit, the draw needles together with their associatedreading needles of one and the same group being thus controllable insuccession by one and the same draw rail, offset by one pick relative toone another.

The two arrester hooks associated with each baulk or with each healdshaft, respectively, are divided into one arrester hook for the evennumbered picks, and one arrester hook for the odd numbered picks, oneworking cycle of the dobby corresponds to two picks.

An object of the invention is to provide a dobby, wherein there arereturned into the starting position the arrester hooks, which had beenadjusted for hooking-on, controlled by the dobby mechanism, so that thisreturning movement takes place at a predetermined velocity, whichgradually diminishes to a standstill, without causing any jerks.

This is attained according to the invention such that the drivingmovement of the draw rail of the group of draw needles for the forwardrun lags behind by a certain rotational angle of the working cycle ofthe dobby relative to the driving movement of the draw rail of the groupfor the reverse run. All draw needles are lifted off twice per workingcycle by a needle lifter such that in the forward 3,381,719 Patented May7, 1968 run the reading by the reading needles and their associated drawneedles for the forward run has taken place before the drawing-outmovement of the associated draw rail, and the drawing-out movement ofthe draw rail for the associated draw needles for the reverse run takesplace before the reading by the corresponding reading needles. Theseoperations take place in the inverse order during the reverse run.

Moreover these arrester hooks, which are to remain in the hooked-onposition during several consecutive working cycles, are to be kept inthis position during the transition from one cycle to the other, andthis should be achieved without any appreciable see-sawing of thearrester hooks.

In order to fulfill these requirements, the working sequences of thevarious components are conveniently so timed to one another, that theirmovements run absolutely symmetrically, and are identical for theforward run as well as for the reverse run.

The angular offset of the working sequences between the movements of thetwo draw rails may be controlled in such a manner thatduring a forwardrun and with an arrester hook, which has been moved into the arrestingposition for the upper shed position of the heald shaft and which has tobe restored to the initial lower shed positionat the moment of thisarrester hook being relieved from the pressure of the pusher rail on theattachment hook, the draw rail of the draw rails for the reverse run isin the drawn-out position, whereby the corresponding draw needles ofthis arrester hook are engaged and are returned in a controlled manner,which prevents the arrester hook from rebounding. Moreover, while thearrester hook remains in the attachment position beyond one workingcycle the draw rail of the draw needles for the reverse run engages thedraw needles of this arrester hook and thus retains in the engagementposition the arrester hook, which has been relieved of the force of thepusher rail, until the draw rail itself of the draw needles for theforward run takes over the retaining by means of its draw needles, sothat substantially a see-sawfree transition of the arrested position cantake place from the draw rail for the reverse run to the draw rail forthe forward run. The control members allowing the same working sequencesfor the reverse run.

A main advantage of the aforesaid offset of the driving movements of thetwo draw rails consists in that a controlled return of an arrester hook,which is in the attachment position and is released by the attachmenthook, is attained in the forward run (and conversely in the reverserun), so that the arrester hook is either restored gradually and withoutjerk to its initial position, or when this same arrester hook is to :berested-in again in the following working cycleis engaged by themechanism for the reverse run, viz, at the moment, when the draw railfor the forward run begins to recede. Any jerky receding is thusprevented.

In the accompanynig drawing an embodiment of the dobby according to theinvention is illustrated by way of example, wherein:

FIG. 1 is a diagram of heald control mechanism in longitudinal section;

FIG. 2 is a detail of FIG. 1 in a perspective view, illustrating readingneedles with associated draw needles and the arrester hook co-operatingtherewith;

FIG. 3 is another detail of FIG. 1 in perspective view illustrating thedrive mechanism of the draw needles;

FIG. 4 is a graph of the movements of the various principal componentsof the dobby in the course of two consecutive working cycles; and

FIG. 5 is a section view of a pattern card.

In FIG. 1, two adjacent jacks of the dobby are denoted by 1 and 1',which are connected by chains 2 and 2 or 3 the like, illustrateddiagrammatically with two associated heald shafts (not shown) of thedobby. The heald shaft corresponding to the jack 1 is in a raisedposition, while the heald shaft corresponding to the jack 1' is in thelowered position hereinafter referred to as the rest position of theheald shaft and jack. The jacks 1 and 1' are mounted movably on a commonaxle 3, against which they are biased by the action of weights orsprings associated with the heald shafts. Each jack has a middle arm 4or 4', respectively, which is pivotally attached at 5 and 5',respectively, on a baulk 6 or 6', respectively. The baulks of all thejacks of the dobby are subject to the action of two pusher rails 7 and 8performing arcuate motions of travel on the two arcs I and I in oppositedirections. The arcs are symmetrical relative to a horizontal plane, andhave centers which coincide with the pivot point 5', which correspondswith the position of the jack 1' in its rest position.

The pusher rails 7 and 8 act on the rear ends of movable attachmenthooks 9 and 9', which are pivotally attached on each baulk end. Thehooks protrude forwardly, i.e., on the sides remote from the jacks 1 and1' (in FIG. 1 to the left), the upper hooks are open upwardly, and thelowerhooks open downwardly.

Considering the baulk 6' associated with the jack 1, which is in therest position, the baulk ends (or more particularly the rear ends of theattachment hooks) contact the pusher rails 7 and 8, respectively, andswing with the same without the centre 5' being displaced, namely insuch a manner that this centre 5 and the jack 1 are retained in theaforesaid rest position, without requiring for this purpose a system offixed abutments as in dobbies having conventional hooks.

The four movable attachment hooks 9 and 9' cooperate alternatively withtwo upper arrester hooks 10 and 10 and with two lower arrester hooks 11and 11', which are pivotally mounted on two axles 12 and 13,respectively, and are biased by springs 14 and 15 into their initialpositions. Each of these arrester hooks has a lever 16, 17, respectively(FIG. 2), which is directed downwardly on the upper hooks, and upwardlyon the lower hooks.

As shown in FIG. 2, each lever 16, 17 has a pin 18, 19, respectively,which protrudes on both sides of the lever and on both sides of whichanchorages 20, 21 and 22, .23, respectively, are pivotally attached.Each anchorage. 20, 21, 22, 23 is at the same time the carrier of a drawneedle 28, 29 and 30, 31, respectively, and of a wire spring 24, 25 and26, 27, respectively. The end of each draw needle is turned up in theshape of a hook.

For the sake of clarity, in FIG. 2 only those anchorages, springs anddraw needles are shown, which are associated with the arrester hooks 10and 11 and cooperate with the baulk 6. Accordingly, the componentsassociated with the second baulk 6 illustrated in FIG. 1 are omitted inFIG. 2.

As illustrated in FIG. 1, the wire springs 24 and 26 rest on atransverse bar 32, and the wire springs 25 and 27 rest on a transversebar 33, so as to pull the corresponding draw needles 28-31 downward. Thefree ends of the draw needles accordingly rest on the two draw rails 34and 35, which are mounted reciprocatably one above the other. The lowerdraw rail carries the draw needles 28 and 3t and the upper draw rail 35carries the draw needles 29 and 31.

Moreover two needle lifters 36 and 37 are mounted vertically movableunderneath the draw needles in order to lift the same, i.e., the needlelifter 36 lifts the draw needles 28 and 30, and the needle lifter 37lifts the draw needles 29 and 31. Both needle lifter-s 36 and 37 movesimultaneously and lift all reading needles off the pattern card.

On each of the draw needles 28-31 one reading needle 3841 is suspended.As shown in FIG. 2, each reading needle is guided in a verticaldirection by two perforated needle guides 42 and 43. Each reading needleis coiled one-and-a-half-times about the associated draw needle, and itsend penetrates through the upper needle guide 42 as a safeguard againstturning. The lower ends of the reading needles 3841 read a perforatedpattern card 44, which is advanced stepwise by the usual pattern cardcylinder 45.

As shown in FIGS. 1 and 2, the reading needles are arranged in fourrows, the first row comprising the reading needles 39 co-operating withthe draw needles 29, which are in operative connection with the upperdraw rail 35 and accordingly also with the upper arrester hooks 10. Thesecond row comprises the reading needles 41 cooperating with the drawneedles 31 which are in operative connection with the same upper drawrail 35, but cooperate with the lower arrester hooks 11. The third rowcomprises the reading needles 3-8 Ofthe associated draw needles 28,which co-operate with the lower draw rail 34 and with one of the upperarrester hooks 10. Finally, the fourth row comprises the reading needles40 of the associated draw needles 30, which co-operate with the lowerdraw rail 34 and with one of the lower arrester hooks l1. Summing up,the first and third row of reading needles co-operates with the upperarrester hooks, while the second and fourth row cooperates with thelower arrester hooks; in other words, the first and second rows areassociated with the upper draw rail, while the third and fourth rows areassociated with the lower draw rail.

The guiding and advancing of the pattern card 44, which is provided withdriving holes 78 (FIG. 5), is effected by the cylinder 45, whose teethengage in these driving holes. After every second revolution of thecrank shaft of the dobby the cylinder advances the card by two picks,the pattern card 44 having for each pick a row 1-20 (FIG. 5) of readingpoints, and two lines of reading points it and g, running in thedirection of movement of the card, associated with odd numbered and evennumbered picks, respectively. In FIG. 5 the reading points are eachmarked by a cross, the reading needles 40, 38, 41 and 39 just readingfor example the 9th, 10th, 11th and 12th pick. The picks 9 and 10 hadbeen read before the last preceding advance of the card by the readingneedles 41 and 39 for the forward run, thus controlling the position ofthe draw needles 31 and 29 which in turn controlled the position of thearrester hooks 11 and 10. Depending on the position of the arresterbooks, the attachment hooks 9 were either released or switched back,whereby through the baulk 6 and the lever 4 the heald was brought intothe position corresponding to the pattern ca-rd. After the advance stepof the card into the position shown, these same reading needles 41 and39 read the next two picks 11 and 12 for the forward run. The control ofthe same heald shaft is effected in the manner described hereinabove.While the reading needles 41 and 39 now read the picks 11 and 12 for theforward run, the reading needles 40 and 38 for the reverse run read thereading points for the rows of picks 9 and 10. These latter readingneedles 40 and 38 control, in accordance with the invention, the returnof the arrester hooks 11 and 10 through their associated draw needles 30and 28.

The needle lifters 36 and 37 periodically lift through the draw needles28-31 all the reading needles 38-41 beyond the pattern card, namelyshortly before any advance step of the pattern card cylinder; then thereading needles are lowered again, in order that the reading can beperformed and that the reading needles dropping into the perforations ofthe card control again the draw needles. Those draw needles, which areretained in the upper position by the pattern card, are exempt from theaction of thedraw rails 34 and 35, while those draw needles, whosereading needles drop into perforations of the pattern card, are carriedalong by the draw rails and are pulled to the left, whereby thecorresponding arrester hooks and 11 are tipped and accordangly come intooperative connection with the attachment hooks 9. These attachment hooks9 are thereby arrested and connot return together with their associatedpusher rail. Consequently, when the opposite end of the baulk 6 ispushed forward by the corresponding pusher rail, the middle joint 5 ofthe baulk will be displaced, and will raise the associated heald shaftthrough the jack 1, which is pivotally attached to it. In the positionof FIG. 1, the lower attachment hook '9 is detained by the lowerarrester hook 11, so that the forward movement of the upper pusher rail7 effects a movement of the jack 1, which through chain 2 raises thecorresponding heald shaft.

Lifting off of the needles takes place pick after pick, while theadvancing of the cylinder takes place only after every second pick. Atevery pick the draw needles are lowered by the needle lifters, so thatthe reading needles contact the pattern card and drop in thecorresponding perforations thereof.

The draw rails 34, 35, which draw out the lowered draw needles, areconstructed as toothed racks (FIG. 3). Their pitch corresponds to thepitch of the dobby, i.e. to the pitch of the heald shafts. Accordinglythe toothed rack has one tooth and one interstice or recess for eachpitch. The lateral distance of two draw needles lying side by side andassociated with one and the same heald shaft amounts to half a pitch,alternately one draw needle controlling the upper arrester hook andattachment hook, respectively, and the other draw needle controlling thelower arrester hook and attachment hook, respectively. The toothed racks34, 35 are then moved to-and-fro pick after pick in the sense of adrawing-out movement of the draw needles. Prior to any drawing-outmovement a lateral displacement of the toothed rack takes place by onehalf pitch, so that at the reciprocating drawing-out movement only onehalf of the associated draw needles is engaged by a tooth of the toothedrack. In one lateral positiondepending on the reading of the readingneedles-the draw needles of the upper arrester hooks and attachmenthooks, respectively, are accordingly engaged by the teeth of the toothedracks, while the other draw needles remain ineffective due to theirdipping into the recesses for the control of the arrester hooks andattachment hooks, respectively, and thus of the heald shafts.

Since all the reading needles are lowered twice by the needle lifters 36and 37 for each working cycle and the same position of the pattern cardfor the purpose of reading, the draw rails have to perform likewise twotoand-fro movements per working cycle, controlling once one arresterhook and the other time the other arrester hook for each baulk.

In FIG. 3 there are illustrated the draw rails 34 and 35 with theircontrol mechanism and the draw needles 29 and 31 of the upper row lyingside-by-side. In the drawn-out position as shown the draw rail 35 canact only on the draw needle 29, since the draw needle 31 is located infront of a recess; the draw rail 35 is capable of being displaced half apitch transversely of the dobby in its non-drawn position, so that inthe next subsequent drawing-out movement the draw needle 31 is engaged,while the draw needle 29 stands in turn in front of an interstice orrecess.

The eccentric shaft 46, which turns at half the speed of the crankshaftof the dobby, i.e. makes one revolution per any two picks, carries afirst cam 47 having a cam groove 47a, in which engages a follower roller48 journalled on an arm 49, which is pivotally mounted on a fixed axle50. A double-armed lever comprising the arm 49, hub 51 and a second arm52 carries at one arm the follower roller 48 engaging in the cam groove47a, and on the other arm the control roller 53-, which through a wedge54 and push rod 55 and acting against the bias of a compression spring59, displaces the two draw rails 34 and 35 half a pitch in thetransverse direction.

A push rod 55 slides in two lateral jaws 56 of the dobby frame. On thispush rod 55 two lugs 57 are keyed, which are mounted slidably on fixedconnecting bar 58 of the jaws 56. The juxtaposed surfaces of the lugs 57have horizontal grooves 57a serving as guides for the ends of the drawrails 34 and 35. The spring 59 arranged on the push rod 55 between thejaws 56 and collar 77 on the rod constantly biases the wedge 54 againstthe control roller 53.

Moreover the eccentric shaft 46 carries on each side of the dobby framea cam 60, which is contacted by two follower rollers 61 and 62. Theserollers are associated with two levers 63 and 64 arranged crosswise,whose hubs 65 and 66 are pivotally mounted on two pins 67 and 68 rigidlymounted on the adjacent jaw 56. Each hub 65, 66 carries a second lever69, 70 respectively connected by a push rod 71, 72, respectively, withthe adjacent end of the draw rail 34 and 35, respectively. Two returnsprings 73 and 74 are provided, which ensure the contact of the followerroller 61 and 62 with the cam 60. The mounting of the push rods 71 and72 is so arranged, that they are pivotable by a certain rotationalangle, in order to allow a lateral displacement of the draw rails 34 and35. Due to the angular'offset of the follower rollers 61 and 62 relativeto the cam 60, which rotates in the direction of the arrow, the secondfollower roller (which corresponds to the draw rail 35) slightly lagsbehind the first one (which corresponds to the draw rail 34).

When the eccentric shaft 46 rotates, the controlling roller 53 isoscillated by the cam 47, and accordingly moves the two draw rails 34and 35 to-and-fro transversely of the dobby through the action of thewedge 54 and the lugs 57. The cam 47 is so shaped, that during thisalternating movement the two draw rails come to a short standstill anytime they reach the ends of their path. At the same time, the cam 60effects, by means of the follower rollers 61 and 62 and of the push rods71 and 72, a fore-and-aft movement of the draw rails in the longitudinaldirection of the dobby, likewise with a short standstill at each endposition, this movement taking place twice for each revolution of theeccentric shaft 46, since the cam 60 has two maxima. Moreover thismovement has a relative phase offset, the draw rail 35 lagging slightlybehind the draw rail 34. The relative position of the cams 47 and 60 issuch, thatwith the aforesaid phase offsetthe draw rails 34 and 35 movetransversely during their standstill periods in the non-drawn position.

In order to explain the manner of operation of the dobby according tothe invention, be it assumed that a single draw needle is associatedwith each attachment hook, e.g. the draw needles 29 and 31, whichcorrespond to the upper draw rail. In this case the lower draw rail 34with its draw needles 28 and 30 and corresponding components is omitted.

In the motion graph A of FIG. 4, the needle lifter (i.e. then only theneedle lifter 37) has lifted at the moment to the draw needles 29 and31, whereby simultaneously the associated reading needles 39 and 41 arelifted, and the pattern card 44 on the cylinder 45 is released. At thismoment the pusher rails 7 and 8 are half way on their path, as shown inthe double graph B.

The draw rail 35 is then in its non-drawn position (graph C) and in themiddle of its transverse displacement (graph D). At the same time thepattern card cylinder 45 advances a new double pick unit, as followsfrom graph E.

For the sake of simplicity be it assumed, that all the arrester hooks 10and 11 are in their initial positions 10' and 11, in which their levers16 and 17 contact the abutment 76 (FIG. 1).

At the moment t the needle lifter has lowered itself (graph A), and thereading needles have read the new double pick unit of the pattern card,which then stands still on the cylinder 45. The reading needles of thedraw needles 29 and 31 have dropped into perforations of the card. Thepusher rails 7 and 8 have almost reached the 7 end of their movement(graph B), while the draw rail 35 stands yet in its non-drawn position(graph C).

While the pusher rails '7 and 8 have arrived in their end positions andremain there (i.e. for example in the position of FIG. 1, wherein thepusher rail 7 is advanced and the psher rail 8 is redrawn), the drawrail 35 advances graph C) and acts in this case on the draw needle 2.)of the upper arrester hook which at this moment is located in front of atooth of the toothed rack (FIG. 3). Those draw needles, whose readingneedles have dropped into a perforation of the pattern card, areaccordingly pulled out, which effects a resting-in of the correspondingupper arrester hook 10. This corresponds to the moment t in which thedraw rail 35 reaches the end of its forward movement (graph C).

At the moment t the pusher rails 7 and 8 begin their return movement,rail 7 receding, and 8 advancing (graph B). Almost at the same time thedraw rail 35 begins its return movement (graph C) and releases again thear rester hook 10, so that the hook 10 could be raised by the bias ofthe spring 14. However, this arrester hook has in the meantime rested-inin the corresponding attachment hook 9, and connot respond to the springbias. It remains accordingly in the working position and retains thecorresponding hooked-on end of the baulk 6, so that the lower pusherrail 8 effects the advance of the pivot point 5 and the raising of theheald through the jack 1.

Shortly after the moment t the needle lifter begins to lift the drawneedles (graph A). After release of the draw rail 35 from the drawneedles this rail begins its transverse displacement (graph D). In thisway the moment L is reached, at which the pusher rails 7 and 8 (graph B)are again half-way on their path, however, in the inverse workingmovement as compared with t Thus the end of the first half of theworking cycle of the draw needle 2? is attained, which cooperates withthe reading needle 39.

Then a new half working cycle begins, still with the same reading,wherein this time the draw needle 31, which during the first half cyclehad remained inactive, is involved, namely with its reading needle 41for the second row of perforations of the pattern card. The needlelifter lowers itself again (graph A), and at the moment t also thereading needle is lowered so as to read again the pattern card. The drawrail 35 moves forward a second time (graph C); however, since it hadbeen displaced transversely, it engages only the draw needle 31.

At the moment the draw rail has terminated its forward movement, and thelower arrester hook is in a position for resting-in in the correspondingattachment hook 9. The same operation is repeated as describedhereinabove, but this time it is the upper pusher rail 7, which by itsadvance effects the raising of the heald.

The needle lifter rises again (graph A), the draw rail 35 recedes (graphC) and then displaces itself transversely (graph D). The card cylinder45 advances by a double pick unit (graph E). The complete working cycle,which comprisestwo picks, is accordingly finished, and the startingmoment t is reached again.

In the course of the working cycle described, the draw rail 35 alone hasset in operation, in succession, the draw needle 31 for the ninth (FIG.5) or odd numbered pick of the dobby, and subsequently the draw needle29 for the tenth or even numbered pick.

At the beginning of the explanation of the manner of operation of thedobby according to the invention, it had been assumed, that the patterncard was perforated throughout. This is, however, not the case inpractice.

Consequently, any time the needle lifter lowers itself, some readingneedles 39 and 41 are kept in the upper position, so that their drawneedles 29 and 31 are not influenced and the corresponding heald shaftsare not raised, the reading taking place once for the odd numbered pick,and a second time for the even numbered pick.

From the preceding explanations it might be deduced, that the dobbycould theoretically function normally without the lower draw rail 34,the draw needles 28 and 30 and the reading needles 38 and 40. Thismanner of operation does not demand either, that the needle lifters 36and 37 are set in motion twice per double pick uuit,since the reading bythe reading needles immediately before the moment t sufiices, and neednot be repeated immediately before the moment t A dobby so equippedwould however have serious disadvantages in practice which would badlyaffect its use. Considering the case of an arrester hook, which in thecourse of the cycle described had been brought into the engagementposition (cg. arrester hook 10). The same could return in the nextcycle, depending on its control by the pattern card, to its initialposition or, on the contrary, remain in the engagement position.

In the first case (always assuming the lower draw rail 34 and associatedcomponents to be omitted) the corresponding draw needle 29 would belifted shortly after the moment t and before the beginning t of thefollowing cycle. since the corresponding arrester hook is at this momentrested-in in the attachment hook, it does not react to the spring 14which tends to release it. However, at the moment t the pusher railpushes the attachment hook 9 beyond its position of engagement with thearrester hook 10, whereby a temporary disengagement of the attachmenthook 9 from the arrester hook 10 occurs, so that with the assumedarrangement the arrester book 10 with its draw needle would suddenlyjerk back by the action of the spring 14, which would cause anundesirable jerky movement of the control mechanism of the dobby. Inorder to obviate this, bulky and sensitive shock absorbers would have tobe provided for the arrester hooks 10 and 11.

When however the arrester hook 10 should remain in the engagementposition during the subsequent cycle, the situation would be even moreunfavorable. At the moment t the arrester hook would be released, whilethe corresponding draw rail 35 were just beginning its for-,

ward movement in order to act on the draw needle 29 and to bring theattachment hook into the engagement position. Thus results a blow of theturned-up end of the draw needle on the corresponding tooth of the drawrail. Tests made with such an arrangement have shown, that at theworking speeds of modern dobbies this leads to the destruction ofmaterials, particularly of the draw needles.

Finally a dobby so constructed could not perform a reverse run asrequired for the mechanical dissolution of weaving faults in the fabric.From FIG. 4 it will be seen, that in a reverse run (i.e. proceeding fromthe right to the left) the needle lifter 37 (graph A) is lowered onlyafter the draw rail 35 (graph C) has begun to advance. This draw railcannot therefore influence its associated dropped-in draw needles 29 and31, i.e. these dropped-in draw needles would rest on top of the drawrail instead of being carried along by it. In other words, the droppedinposition of the draw needles would be annulled, since the draw rail doesnot carry along the draw needles in its to-and-fro movement. Accordinglyneither a selection of the arrester hook nor the appropriate opening ofthe shed can be carried out.

In order to counter these disadvantages, the additional provision of thedraw rail 34, draw needles 28 and 30 and reading needles 37 and 40 hasbeen made. As follows from FIG. 4, the draw rail 34, which could becalled the draw rail for the return run, in the normal run of the dobby(i.e. from left to right in FIG. 4) begins the drawing-out movementslightly before the draw rail 35 (or draw rail for the forward run); inthe embodiment described, the phase advance of the drawing-out movementof the draw rail 34 relative to the draw rail 35 amounts approximatelyto 40 in relation to the eccentric shaft 46 of the dobby. Hence the drawrail 34 for the reverse run advances (graph F) before the needle lifter36 and 37 (graph A) has been lowered in order to carry out the readingby the reading needles. Consequently it slides through underneath theturned-up ends of the draw needles 28 and 30 without affecting the same.In principle, everything occurs, as if the entire reverse runarrangement 34-28-30-38-40 did not exist. The manner of operation of thedobby is theoretically the same as described hereinabove.

In the reverse run (i.e. from right to left in FIG. 4) the workingsequences of the two arrangements for forwardand reverse-running areexactly the inverse. The drawing-out movement of the draw rail 35 (graphC) begins before the beginning of the lowering movement of the needlelifters 36 and 37 (graph A), while on the other hand the dropped-in drawneedles are carried along by the draw rail 34. In order that the healdshafts move in the right sequence in the reverse run, consequently thereading needles 38 and 40 for the reverse run have to read the samepoint in the pattern card, which previously had been read by the needles39 and 41 during the forward run. Due to the double action of the needlelifters 36 and 37 the reading takes place between the moments and tanalogous'to the moments t and t at the forward run.

If a vertical line drawn at the moment L, of FIG. 4 is considered anaxis of symmetry for the movement of the pusher rails 7 and 8 (graph B)it will be realised, that this vertical line is also an axis of symmetryfor the movements of the needle filters 36 and 37 (graph A), and thatthe graphs C and F for the draw rails 35 and 34 have a phase offset,namely the draw rail 34 (graph F) by 40 compared with the draw rail 35(graph C) (FIG. 4, 275 to 315). There exists accordingly symmetry of theworking sequences in the sense, that each graph C or F for the forwardrun (or reverse run) is identical with the graph F or C for the reverserun (or forward run), respectively. When, as assumed before, each cardshows the pattern for the needles reading the reverse run, which thepreceding card contain for the needles reading the forward run, thissymmetry exists also for the reading, so that the shed formation isidentical for the reverse run and for the forward run.

In this manner and with suitable adjustment the aforesaid disadvantages,such as destruction of material and jerky movements, are obviated by adobby having two draw rails and two draw needles associated with eacharrester-hook.

Moreover, a dobby so constructed allows at any time a change of thesense of rotation from forward running to reverse running and viceversa, while maintaining the right sequence of heald shaft movements andwithout requiring any interference by the operative personnel with themechanism.

In a working cycle, wherein the arrester hook 10 is in engagement Withthe attachment 9 (cycle t tand wherein these hooks are to be disengagedfrom each other in the subsequent cycle, the draw rail 34 for thereverse run is in the advanced position at the moment t (graph F) atwhich the arrester hook is released by the pushing movement of thepusher rail 7. Since on the other hand the reading needles 38 and 40 forthe reverse run read the pattern for the for forward run of thepreceding pattern card, the needle 38 is lowered; consequently, when thehooks are disengaged, the associated draw needle 28 for the reverse runwill at once abut the almost drawn-out draw rail 34, which retains thedraw needle for a moment and subsequently brings it gradually again intothe tarting position, without any jerky movements occurring at all.

When however the arrester hook 10 has to remain in the engagementposition in the following working cycle (i.e. in the cycle beginning atthe moment t the corresponding draw needle 28 for the reverse run isretained by the draw rail 34 for the reverse run, namely until themoment t when the draw rail 35 for the forward run (graph C) arrives atthe drawn-out position, in order to take over the arresting of theattachment hook for the forward run. The arrester hook 10 hasaccordingly not returned to the initial position, but is simply retainedin the engagement position, the draw rail 35 taking over the retainingfrom the draw rail 34. Thus a jerky movement of the arrester hook 10 andassociated components, as well as any unnecessary intermediate movementis obviated, since in the transiton from one working cycle to the nextone a controlled return movement of the attachment hook, or itsremaining in the engagement position, is safeguarded.

What I claim is:

1. In a double lift dobby, a plurality of jacks for operating respectivehealds, a plurality of baulks associated with respective jacks, pusherrails driven to-and-fro out of phase for each double pick correspondingto a 360 working cycle of the dobby and engaging respective ends of eachbaulk to drive its ends in opposite directions, attachment hookspivotally mounted two each on respective baulks for arresting ofrespective ends of said baulks, arrester hooks actuatable for arrestingrespective ones of said attachment hooks in extreme forward positions ofsaid ends of said baulks, said extreme forward positions of said ends ofsaid baulks corresponding to a position in which a respective heald isoperated to a raised position, said arrester hooks comprising twoarrester hooks for each baulk, for each baulk for arresting thereof fourdraw needles comprising two groups of draw needles having for eacharrester hook a pair of draw needles each connected thereto andbelonging to a separate one of said groups and operable when beingdrawnout forwardly for actuation of a respective arrester hook to aposition arresting a respective baulk end, a plurality of readingneedles each associated with a respective draw needle for in operationreading pattern means controlling drawing-out of said draw needlesthereby to control arresting of said baulk ends, needle lifters forlifting said reading needles clear of said pattern means twice in eachworking cycle of said dobby, draw rails operable for drawing-out saiddraw needles to effect actuation of the respective arrester hooks forengaging respective attachment hooks for arresting said ends of saidbaulks in said extreme forward position, means operating said draw railsto effect drawing-out forwardly of said groups of draw needles of agiven baulk out of phase by a double pick and the draw needles of a samegroup out of phase by one pick in the working cycle of said dobby toarrest the respective baulk ends in dependence upon the readings of saidreading needles, said draw rails comprising a draw rail operablereciprocably effective for forward operation of said dobby drawing-outdraw needles of one group of said groups of draw needles correspondingto reading needles for forward operation of said dobby and a draw railoperable reciprocably effective for reverse operation of said dobbydrawing-out forwardly draw needles of the other group of said group ofdraw needles corresponding to reading needles for reverse operation ofsaid dobby, means in said means operating said draw rails drawing outsaid rails reciprocably forwardly and operating them backwardly and foreffecting drawing-out forwardly of the draw needles associated therewithwhen the corresponding reading needles have effected reading of saidpattern, means restoring said draw needles to a retracted position fromwhich they are drawn out forwardly, means for causing a sequence inforward operation of said dobby of reading of said pattern by saidreading needles for forward operation, drawing-out forwardly of saidrail effective for forward operation of said dobby, drawing-outforwardly of said rail effective for reverse operation of said dobby,reading of said pattern by said reading needles for reverse operation,and including means reversing said sequence in reverse operation of saiddobby.

2. In a double lift dobby according to claim 1, in which said meansoperating said draw rails comprises means driving said draw railsreciprocably drawing-out said draw needles in one direction of movement,said draw rails and said drawing needles being disposed relatively for agiven draw rail drawing-out a same pair of drawing needles correspondingto a same group of draw needles connected to the arrester hooks of agiven banlk.

3. In a double lift dobby according to claim 2, in which said draw railscomprise two draw rails and in which said means operating said drawrails comprises means driving said two draw rails reciprocably and agiven draw rail drawing-out draw needles of a given group only andalternately with smooth transfer from one draw needle to the other drawneedle of said group to smoothly actuate a respective arrester hook forarresting a respective baulk end and retaining it arrested underalternate control of both of said draw needle groups in dependence uponreadings of said reading needles.

4. In a double lift dobby according to claim 3, in which said meansdriving said draw rails comprises means operative in timed relation withsaid needle lifters and said pusher rails drawing-out draw rails of agiven group and returning said draw needles to a position to which arespective arrester hook is returned smoothly to a rest position inwhich it is out of engagement with a respective attachment hook andcorresponding to a condition in which a heald associated with arespective baulk is in a lowered position, and means constantly biasingthe individual arrester hooks to said rest position.

5. In a double lift dobby according to claim 3, in which said meansdriving said draw rails comprises means operative in timed relation withsaid needle lifters and said pusher rods and operative to eifectout-ofphase reciprocation of said draw rails with one draw rail laggingthe other, and in which said pattern means is advanced for reading bysaid reading needles at completion of each cycle of said dobby.

References Cited UNITED STATES PATENTS 2,751,938 6/ 1956 Staubli et a1139-68 FOREIGN PATENTS 657,967 3/ 1938 Germany.

2,785 1909 Great Britain. 264,873 2/ 1950 Switzerland.

HENRY S. JAUDON, Primary Examiner.

